Cos 8 Degrees

Sin, Cos, Tan, Cot of an Angle
Function
Angle (°)

What is cos 8°?

Answer

cos 8° ≈
0.9903

Angle in radians: 8° = 2π/45. The point of the angle is in quadrant I, where cosine is positive.

≈ — rounded to 4 decimal places. cos 8° can't be written with square roots: 8° is not a multiple of 3°.

P(cos 8°, sin 8°) ≈ (0.9903, 0.1392)

xyOP

P(cos 8°, sin 8°) ≈ (0.9903, 0.1392)

Highlighted: the projection on the x-axis — cosine, x ≈ 0.9903.

All four functions of 8°
FunctionExact valueDecimal
sin 8°—≈ 0.1392
cos 8°—≈ 0.9903
tan 8°—≈ 0.1405
cot 8°—≈ 7.1154

See Also

Recalculate with different values ↑

Cosine of nearby angles

Anglecos
5°≈ 0.9962
6°≈ 0.9945
7°≈ 0.9925
8°≈ 0.9903
9°≈ 0.9877
10°≈ 0.9848
11°≈ 0.9816

FAQ

What is cos 8°?

cos 8° ≈ 0.9903

Why does cos 8° have no exact value?

A trigonometric value of a whole number of degrees can be written with square roots only when the angle is a multiple of 3°. 8° is not, so no such exact form exists; the value is used as a decimal: cos 8° ≈ 0.9903.

Why does a calculator show −0.1455 for cos 8?

The calculator is in radian mode (RAD): it takes cos 8 as the cosine of 8 radians, cos 8 rad ≈ −0.1455. Switch it to degrees (DEG): cos 8° ≈ 0.9903. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

See Also